65 lines
1.9 KiB
JavaScript
65 lines
1.9 KiB
JavaScript
/**
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* Copyright (c) 2015-present, Facebook, Inc.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*
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* @providesModule Subscribable
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* @flow
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*/
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'use strict';
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import type EventEmitter from 'EventEmitter';
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/**
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* Subscribable provides a mixin for safely subscribing a component to an
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* eventEmitter
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*
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* This will be replaced with the observe interface that will be coming soon to
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* React Core
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*/
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const Subscribable = {};
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Subscribable.Mixin = {
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UNSAFE_componentWillMount: function() {
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this._subscribableSubscriptions = [];
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},
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componentWillUnmount: function() {
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// This null check is a fix for a broken version of uglify-es. Should be deleted eventually
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// https://github.com/facebook/react-native/issues/17348
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this._subscribableSubscriptions && this._subscribableSubscriptions.forEach(
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(subscription) => subscription.remove()
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);
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this._subscribableSubscriptions = null;
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},
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/**
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* Special form of calling `addListener` that *guarantees* that a
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* subscription *must* be tied to a component instance, and therefore will
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* be cleaned up when the component is unmounted. It is impossible to create
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* the subscription and pass it in - this method must be the one to create
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* the subscription and therefore can guarantee it is retained in a way that
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* will be cleaned up.
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*
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* @param {EventEmitter} eventEmitter emitter to subscribe to.
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* @param {string} eventType Type of event to listen to.
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* @param {function} listener Function to invoke when event occurs.
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* @param {object} context Object to use as listener context.
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*/
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addListenerOn: function(
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eventEmitter: EventEmitter,
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eventType: string,
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listener: Function,
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context: Object
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) {
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this._subscribableSubscriptions.push(
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eventEmitter.addListener(eventType, listener, context)
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);
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}
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};
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module.exports = Subscribable;
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